GOLD RESOURCE CORP

Andesite: · An extrusive igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture characteristic of subduction zones, such as the western margin of South America.

Concentrate: · A product from a mineral processing facility, such as gravity separation or flotation, in which the valuable constituents have been upgraded and unwanted gangue materials rejected as waste.

Cut and Fill: · A mining method where ore is removed in horizontal slices, and each mined-out area is backfilled before mining the next level. The fill provides support and a working platform. This method is highly selective and works well in narrow, steep, or irregular ore bodies. Ore is typically loaded and hauled using load, haul, dump machine (“LHD”) equipment.

Doré: · Composite gold and silver bullion, usually consisting of approximately 90% precious metals that will be further refined to separate pure metals.

Drift: · A horizontal tunnel generally driven within or alongside an ore body and aligned parallel to the long dimension of the ore.

Epithermal: · Used to describe gold deposits found on or just below the surface close to vents or volcanoes, formed at low temperature and pressure.

Exploration: · Prospecting, sampling, mapping, diamond-drilling, and other work involved in locating the presence of economic deposits and establishing their nature, shape, and grade.

Grade: · The concentration of an element of interest expressed as relative mass units (percentage, ounces per ton, grams per tonne (“g/t”), etc.).

Hectare: · A metric unit of measurement, for surface area. One hectare equals 1/200th of a square kilometer, 10,000 square meters, or 2.47 acres. A hectare is approximately the size of a soccer field.

Long-hole Stoping: · Mining method which uses holes drilled by a production drill to a predetermined pattern by a mining engineer. Long-hole stoping is a highly selective and productive method of mining and can cater for varying ore thicknesses and dips (0 - 90 degree). Blasted rock is designed to fall into a supported drawpoint or be removed with remote control LHD.

Net Smelter Return(“NSR”): · The net revenue that the owner of a mining property receives from the sale of the mine’s metal products, less transportation and refining costs. As a royalty, it refers to the fraction of net smelter return that a mine operator is obligated to pay the owner of the royalty agreement.

Mineral Deposit: · Rocks that contain economic amounts of minerals in them and that are expected to be profitably mined.

Tonne: · A metric ton. One tonne equals 1000 kg. It is equal to approximately 2,204.62 pounds.

Volcanogenic: · Of volcanic origin.

Volcanic domes: · These are mounds that form when viscous lava erupts slowly and piles up over the vent, rather than moving away as lava flow. The sides of most domes are very steep and typically are mantled with unstable rock debris formed during or shortly after dome emplacement. Most domes are composed of silica-rich lava, which may contain enough pressurized gas to cause explosions during dome extrusion.

Overview

The Company classifies its mineral properties into three categories: “Production Stage Properties,” “Development Stage Properties,” and “Exploration Stage Properties.” Production Stage Properties are properties for which the Company operates a producing mine.

At the Don David Gold Mine, the Company currently has 100% interest in six properties, including two Production Stage Properties and four Exploration Stage Properties, located in Oaxaca, Mexico, along the San Jose structural corridor. Because of their proximity and relatively integrated operations, the Company collectively refers to the six properties as the Don David Gold Mine. The two Production Stage Properties are the only two of the six properties that make up the Don David Gold Mine that the Company considers to be independently material at this time. Please see Item 2. Properties —Don David Gold Mine for further discussion of the properties.

The Company also has 100% interest in the Back Forty Project, an advanced Exploration Stage Property, located in Menominee County, Michigan, USA. The Company does not consider the Back Forty Project to be independently material to the Company at this time. Please see Item 2. Properties— Back Forty Project for further discussion of the property.

Mineral Resources

Under Regulation S-K 1300, a “Mineral Resource” is defined as a concentration or occurrence of material of economic interest in or on the Earth’s crust in such form, grade or quality, and quantity that there are reasonable prospects for economic extraction. A Mineral Resource is estimated based on geological evidence and sampling and considers relevant factors such as cut-off grade, mining method, mining dimensions, metallurgical recovery, location, and continuity, under assumed and justifiable technical and economic conditions. Mineral Resources do not have demonstrated economic viability.

The following tables summarize the estimated Mineral Resources at DDGM and at Back Forty:

Don David Gold Mine – Summary of Gold, Silver, and Base Metal Mineral Resourcesat December 31, 2025(1)(2)(3)(4)(5)(6)

Description · Tonnes(k/t) · Gold(g/t) · Silver(g/t) · Copper(%) · Lead(%) · Zinc(%) · Cut-off grade · Metallurgical Recovery (%)

Arista · $/Tonne · Au · Ag · Cu · Pb · Zn

Measured Mineral Resources · 3 · 1.40 · 192.3 · 0.32 · 1.04 · 4.22 · 150 · 71.3 · 85.0 · 58.9 · 65.8 · 76.3

Indicated Mineral Resources · 60 · 1.66 · 248.6 · 0.27 · 1.78 · 5.41 · 150 · 71.3 · 85.0 · 58.9 · 65.8 · 76.3

Measured + Indicated · 63 · 1.65 · 245.7 · 0.28 · 1.74 · 5.35 · 150 · 71.3 · 85.0 · 58.9 · 65.8 · 76.3

Inferred Mineral Resources · 1,366 · 0.84 · 128.0 · 0.23 · 1.25 · 3.69 · 150 · 71.3 · 85.0 · 58.9 · 65.8 · 76.3

Alta Gracia · AuEq (g/t)

• Competition in the mining industry is intense, and the Company has limited financial and personnel resources with which to compete.
• Estimates of Proven and Probable Mineral Reserves and Measured and Indicated Mineral Resources include some uncertainty, such that the volume and grade of ore actually recovered may vary from the Company’s estimates.
• Products processed from the Company’s operating mines or other mines in the future could contain higher than expected contaminants, thereby negatively impacting the Company’s financial condition.
• Continuation of the Company’s mining and processing activities is dependent on the availability of sufficient water supplies to support its mining activities.
• The nature of mineral exploration, mining, and processing activities involves significant hazards, a high degree of risk, and the possibility of uninsured losses.
• Revenue from the sale of metal concentrate may be materially adversely affected by loss or damage during shipment and storage at the Company’s buyer’s facilities.
• A significant delay or disruption in sales of doré or concentrates as a result of the unexpected disruption in services provided by smelters or refiners could have a material adverse effect on results of operations.
• The Company relies on contractors to conduct a significant portion of the Company’s exploration, development, and construction projects.
• Risks Related to the Company’s Exploration Activities
• The exploration of the Company’s mineral properties is highly speculative in nature, involves substantial expenditures, and is frequently non-productive.
• The Company has acquired and may in the future acquire additional mining properties, and the Company’s business may be negatively impacted if Mineral Resources and Mineral Reserves are not located on acquired properties or if it is unable to successfully execute and/or integrate the acquisitions as planned.
• Regulatory and Geopolitical Risks
• The Company’s operations are subject to ongoing permitting requirements, which could result in the delay, suspension, or termination of its operations.
• The Company’s operating properties located in Mexico are subject to changes in political or economic conditions and regulations in that country.
• Most of the Company’s properties are subject to extensive environmental laws and regulations, which could materially adversely affect its business.
• Climate change and climate change legislation or regulations could impact the Company’s business.
• The Company’s continuing reclamation obligations at its operations could require significant additional expenditure.
• The Company’s ability to develop its Mexican properties is subject to the rights of the Ejido (agrarian cooperatives), and violations of such rights could result in the Company’s loss of title in the subject properties, which would have a materially adverse effect on the Company’s business and financials.
• Title to mineral properties can be uncertain and disputes regarding the title to the Company’s Mexican properties require the Company to litigate such disputes in Mexico, where it faces unfamiliar laws and procedures.
• A significant amount of the Company’s mining properties are subject to exchange control policies, the effects of inflation, and currency fluctuations between the U.S. dollar and the Mexican peso.
• Lack of infrastructure could forestall or prevent further exploration and advancement.
• Risks Related to the Company’s Common Stock
• Volatility in the Company’s stock price could result in shareholders losing part or all of their investment.
• Past payments of dividends on the Company’s common stock are not a guaranty of future payments of dividends.
• Issuances of the Company’s stock in the future could dilute existing shareholders and materially adversely affect the market price of its common stock.
• General Risks
• The failure to complete our announced Transaction with Goldgroup could have a material adverse effect on our business, results of operations, financial condition, cash flows and stock price.
• The Company’s operations may be disrupted, and its financial results may be materially adversely affected by any future pandemic.
• Global and regional political and economic conditions could adversely impact the Company’s business.
• The Company may not be able to operate successfully if it is unable to recruit, hire, retain, and develop key personnel and maintain a qualified and diverse workforce. In addition, the Company is dependent upon its employees being able to safely perform their jobs, but there is risk of physical injuries or illness.
• The Company is dependent on information technology systems, which are subject to certain risks, including cybersecurity risks, data leakage risks, and risks associated with implementation and integration.
• The Company’s business is subject to the U.S. Foreign Corrupt Practices Act and similar worldwide anti-bribery laws, a breach or violation of which could lead to civil and criminal fines and penalties, loss of licenses or permits, and reputational harm.